WinNT/Simda ISecurityEditor usage reconstructed code. It will add new dacl entry <Everyone - Full Control> to specified registry key. If you like you can remove CoCreateInstance etc, they not needed as all this crap already initialized in explorer.exe and they are used here only for debugging, also Simda concats new dacl string to existing, because this is simple example, this is ignored. Additionally no registry values touched, so don't worry for your UAC :)

Just to mention - memory allocated for SDDL string after ISecurityEditor->GetSecurity call must be freed with LocalFree when pps variable is no longer needed. So for your usage extend shellcode to include LocalFree and use it.